[sdiy] Negative voltage references

[ASSI]

On Saturday 19 May 2012, 15:37:10, Tom Wiltshire wrote:
> What do people do for negative voltage references?

A true voltage reference doesn't care what you call it, you can use either 
the positive or negative terminal as the reference voltage.

> Are we expected to use a positive one and stick it through an op-amp?

No, and if you were to do it, you'd need a rather expensive op-amp to get it 
right.

> Or should I just use a 3-pin negative voltage regulator instead? It's not
> great, but it's cheap, and you can get negative ones easily enough.
> REF02's seem to cost £3-£4 each, which I regard as a lot of money for the
> job. A separate regulator costs me £0.30 or so.

There are lots of cheaper voltage references, but be sure to read the 
datasheets (and between their lines) to understand the tradeoffs.  But as I 
said before, voltage references have become so good that they are almost 
always better than what you'd otherwise use in their place.


Regards,
Achim.
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